Lecture-8-Introducti_38192

Lecture-8-Introducti_38192 - IntroductiontoMetabolism...

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n ll’s etabolism nsists of 1000’s of chemical reactions Introduction to Metabolism An cell s metabolism consists of 1000 s of chemical reactions catalyzed by enzymes & organized into a myriad of metabolic athways pathways . Each pathway has this form : rger complex rganic olecules Metabolism manages the material & energy resources of the cell: Larger, complex organic molecules Synthesis via nabolic athways Breakdown via tabolic athways anabolic pathways which are… energy catabolic pathways which are… Example: ample: …energy releasing …energy requiring cellular respiration Example: dehydration reactions Simpler organic molecules Use to form ATP’s Uses ATP’s
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Energy ells require energy to do work: biosynthesis, transport of Cells require energy to do work: biosynthesis, transport of molecules, cellular movements, etc. Energy forms: kinetic, thermal (heat), potential gy , () , p Potential energy: energy matter possesses due to its’ position or structure; e.g., arrangement of atoms in a molecule Chemical energy: potential energy stored in chemical bonds A cell’s metabolism does not create energy, rather it transforms energy from one form to another. How? More potential Potential to kinetic energy energy here… …than down here Convert kinetic to potential energy (walking up stairs)
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he energy transformations that occur within cells is studied Thermodynamics 101 The energy transformations that occur within cells is studied using thermodynamics . – Cells are open systems : exchange matter/energy with its surroundings ( closed systems cannot) 1 st Law: energy cannot be created or destroyed, it is transferred & transformed. Energy lost as heat Chemical nergy energy Kinetic energy Formation of breakdown products 2 nd Law: during energy conversion, a portion of this energy is unusable and lost as heat (No process is 100% efficient). Loss of usable energy = increases the entropy (disorder) of the surroundings
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Free Energy ontaneous rocesses occur without an input of energy; Spontaneous processes occur without an input of energy; they increase the entropy [example: concentrated dye randomly isperses in solution] disperses in solution] . Non spontaneous process requires energy input to proceed; decrease entropy. Whether reactions are spontaneous or not relies on assessing the energy & entropy changes in the system & surroundings. For us, a system = chemical reaction, can define as follows: tal energy = usable nergy + T x unusable nergy Total energy usable energy T x unusable energy enthalpy (H) free energy (G) entropy (S) = + =temperature (in Kelvin K) T =temperature (in Kelvin, K) Free energy (G) can perform work; the value of G determines hether a process is spontaneous or not whether a process is spontaneous or not.
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This note was uploaded on 04/23/2010 for the course BIOL 1361 taught by Professor Knapp during the Spring '05 term at University of Houston.

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Lecture-8-Introducti_38192 - IntroductiontoMetabolism...

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